$5.$ Calculate the Rainfall depths $($Rd$)$ using: $($a$)$ Arithmetic Mean $($AM $-$ no equation given$),$ and $($b$)$Thiessen Polygon $($TPbelow$.(5+10=15$ points$).-$ equation $1)$ methods over a large watershed based on given informationRainfall $($mm$)$Area $($mm$)110140120]100215]150225]225$Egn. $(1)$Where$,$ Rd $-$ Rainfall depth $($mum$),$ A $=$ Total Area $($mim$),$ Al$,$ A$2...$ An $=$ Areas within the watershed $($mm$?),$ PI$.$ P$2....$ Pn $=$ Rain